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- A. J. JAcKMAN a Jan. 3, 1928. 16,845 REFRACTORY ARTICLE AND PROCESS OFMAKING THE SAME Original Filed May 26, 1925 2 Sheets-Sheet l N l I I aLw/L ,l 1 g "TY T'; g g 77% 1;, \YI',

. INVENTOR 2 Sheets-Sheet A. J. JACKMAN Original Filed May 26, 1923REFRACTORY ARTICLE AND PROCESS OF MAKING THE SAME lNV ENTOR LrL /LrLr.

. mw l Rn R1 Jan 3, 192&

' clay,

if they are not carefu fore, liableto dama breakage. Such cruci les,particularly when,

cible rior to use to a tern vitrifi I aw 1m. 3.1m-

UNITED STATES PATENT OFFICE.

an'rmm J'. JAN, 0] FOREST BOROUGH, IENNSY LV ANIA, ASSIGNOIB, TOVISUVIUB OBUCIBLI GOIPANY, OI SWISSVALE, PENNSYLVANIA, A CORPORATION 01PINNBYLVAN Original application fled lay 26, 1988, Serial No. 841,754.-Continued and application tiled August 2,

name-roar an'rrcnn sun raocass or name rm: same.

in; sum No. 728,817. Original no. 1,517,124, dated larch s, 1926.Application 1 reiuue ma Iovenber 82, 1987. Serial No. 885,104.

This application is a continuation of my application Serial No. 641,754,filed May26, 1923.

The present invention relates to refractory 0 articles and moreparticularly to refractory vessels, such as crucibles, saggers and thelike, containing graphite and a ceramic bonding material, and to theprocess of makingthem.

.In makin graphite crucibles, ball clay is usually used as a bond.According to the usual practice now in vogue, after the ware is formed,it is fired in kilns to a temperature lower than the vitrifying. pointof the siderably less than 2000 F. The clay bond being unvitrified willrehydrate in a moist atmos here* and the cruci les are thereforesensitive and liable to spallin particularly ly re eated or annealed bythe user prior to using. Even then such crucibles are liable to spellwhen used. Moreover, such crucibles are relatively soft when put intouse and are, therefrom abrasion and silica sand is used in the mixture,may have formed on them a glaze-like crust m use. Such glaze-like crust,however, is not adherao ant and spalls OR at each heating when thecrucible is used.

In making my improved (graphite crucibles, I emploz a ceramic bonreferably in the nature 0 a porcelain, an urn the, crurature above thecation point of the nding material. This burning is preferably carriedout until there is a substantiall complete maturin and vitrification oft e bonding materia 1 throughout the body of the material. The

so burned will not rehydrate and do not need'to be reheated or annealedby crucibles the user rior to use. The crucible is also y stronger andis less liable to be dama by brea ing in transit before delivery to theuser. A glaze is formed on the surface of the crucible which is integralwith the vitrified bond and which will not spall. Even if the glaze isknocked ofi by rough such temperature being as a I'HIQCOII'.

for iving the crucibles the first burn ;f

Figures 2, 3 and 4 are a horizontal section, a vertical section and anend elevation, respecti'vely, of a continuous kiln for carrymgd out thefinal burning" of the crucibles; an 4' Figure 5 isa tion of suchcontinuous kiln.

I will now describe in detail the preferred rocess of making my improvedcrucibles, 1t bein understood that the invention is not limlted to suchpreferred procedure.

detail section through apor- I take graphite and a ceramic bondingmaterial and mix them together with water in the usual manner and moldthe mix into crucibles in the-usual manner. Graphite may be used aloneas the non-fusing nert constituent or some other non-fusing inert Imaterial maybe mixedwith it, such as silicon carbide, tridymite,zirconium silicate or alumina. The ceramic bonding material ispreferably of a rcelain nature in which the several terial mature orchemically combine into a vitrified bond during the burning of thecrucibles.

, As a typical example of suitable mix, I take graphite, eithercrystalline or flake, 45 parts, settling tank silicon carbide fines 15arts and a porcelain bonding mixture 40 arts. Settling tank siliconcarbide fines constituents of the bonding mais the fine material whichsettles in the tanks after grinding and washing silicon carbide grainsin the manufacture of silicon carbide abrasives. Such fines, exce t foran occasional larger grain, consist o silicon carbide in powdered form.In order to give the resent, e

wellstbnelO ch :5 4 n "I a course,be vsriedtomeetthepsrhculsrusestowhichthecrucibleserepu and various otherfluxing' "entsmsy such as rawdoomite, lime ston 'olite, ,fel be or en er of the so i. ii-'21..

lnln and urned in s non-oxidising, preferably. reducing, shnosphereto upmnnistely 1200 F. In 1 of the w ngs is illustrated a suiteblekilnforpurpose. This'kilnisof the ususl'sort, hs smuf- ,flechsmberl inwhichthe-cm: 2-sre stacked, heated by inthe pusphere in this '7 For thisurpose n ps $5.9m mn I Q pipe g-om e kiln and blowing it t l f'ough .thepipe 7 through the bed of coke 4 which is heatedto incsndescenee sndwhich maintainseredu atmosphere in sllpsrtsofthekilmamndthehlnbenotsbsolutely air be After the wsreis into t e"'I'prefer-to fill the kiln with carbon dioxide which may be conven- 80V p I preferabli maintain s reducing iently introduced from a tank 8 ofuefied carbon dioxide; After-the carbon oxidehasexpelledtheaiinthetenkSisshntofi and the 1 is maincondition by thecirculation the ged'of o This urmng open on, w my ex,- te'nd over a. 0dof several days, thoro y dehy tes the bonding material on in case thebonding mterisl'contsins csrbonst'es, it converts the csrbomtes to theoxide form throughout the mess. The dehydration and reduction ofcslrbonetes, if tive to chernicel combinations which et the highertunperatures ofthe fi'nsl operation. e reducing'etmosphem vents theoxidation of the so,

the crucibles come from operation with the v I were Iinth'ekilnpre-isnowno' lonersusee 'bleto ydration put into usewithburmng ou danger o or mneshng with graphite crucibles asususlthegrsphite in an unreduced um matured fend vitrified P? should.only skin f thirty second u an in abouts hundredthpf an Thessh here,'so

' is preferebl carried oh: in s 'the crucibles, but ould exceed abouttwohours. A

12 in. dimension usually half hour for the oxidiz- The on on Y 33' p'prefersbl not end upon the. mix 13 w the crucible is to of overEmferably at from refer-ably reducing ate surface oxidation is to whichthe n e ILIOI' or the ty of heretofore The" . by heat such a degree ofcompactness of structurebysolution between the constituents of the bondthat the mass as a whole. has the characteristics above pointed out, andis hard, strong and substantially impervious to moisture under normalcondi- 'sists wear and abrasion.. In case the adherent.

tions ofuse. Tests have shown that the hardness of my crucible material-is such that a 10 millimeter hard steel ball under a load of 175kilograms makes an indentation not over 4 millimeters in diameter, andits strength, as determined b breaking a bar approximately one inc 1 suare in cross-section and a four inch span, s ows a modulus of ruptureof over 1500 ounds r uare inch. Ex erienee has emonstrate that such haess and stren th in materials of this class can be developed only byvitrifying the bond under proper conditions as herein described. Theadherent aze formed on the surface of the crucible y the fluxin of thesurface bonding ma-- terial from w ich the graphite was burned duringthe oxidizing heat is formed from the bod of the bonding material and isintegra (y united therewith, there being no line of emareation betweenthe glaze'and the bonding material in the body of the crucible. Thisglaze is entirely different from the surface cunt-like glaze formedonthe crucibles in service by the exudationof silica, which crust-likeglaze readily spalls off of the crucibles. The laze which is formed onmy crucibles is a herent and will not spall off like the crust-likelazes formed on cruciblesi'n. the metal me tin furnaces or like theglazes applied b ipping or painting. 'Tie glaze gives t e crucible alfll'd attractive looking surface substantially free from crazing orcracks and 'which1re-,

aze becomes chip ed ofi inuse, the expose vitneath it immediately formsa glaze when exposed to the heat of the furnace in which the cruciblesare used. Such replacement glaze being formed from the vitrified bondingmaterial is likewise Continued use. of the crucibles made in accordancewith m process .has shown a greatly increased life over crucibles made ythe usual processes now in V e.

In Figures 2 to 5 of the drawings, I have shown a continuous furnace forcarrying out the final burning of the crucibles. This furnace is of thetunnel kiln ty e, consisting of an elongated tunnel of rick work havingtracks 11 along which travel cars 12 bearin he crucibles 2. Thecrucibles travel through the furnace from right to left, as indicated bthe arrows on the drawings. The crucib es first pass into an oxidizingmaterial.

7 in a continuous ortunnel type kiln in which case the first chamber ofsuch kiln would position used in'making my crucibles to.-

chamber 13 in which the are given the oxidizing heat to oxidize eirsurface. They then pass from oxidizing chamber into a chamber 14 inwhich is maintained a nonoxidizing atmosphere and in which the cruciblesare brought up to a temperature above the vitrification point of thebonding The non-oxidizing atmosphere checks the oxidation of thegraphite and serves to protect the: graphite in the body of the cruciblefrom further oxidationduring the final or high temperature firing of thecrucible. The chamber '14 is separated.

from the chamber 13 by baflies 15 which serve to confine the gases ofcombustion and 7'- prevent entry of the oxidizing atmosphere into thechamber 14. also separatedby bafiies 16 from another chamber 17 intowhich are, discharged the gases of combustion from the burners 18 and inwhich the cruciblesare given their final and highest heat. The air forthe burners 18 is restricted so that a reducing atmosphere is maintainedin the chamber. 17. As the gases of combustion pass by the bafiles 16 inthe chamber 14 some secondary combustion takes place, although theatmosphere in the chamber 14 is maintained in a reducing or neutralcondition. Asthegases of combustion pass the baflles 15, furthersecondary combustion takes place, suflicient air being admitted to thechamber 13 to produce an oxidizing atmosphere therein. The cruciblespass from the chamber '17 intoan annealing'chamber 19 fron 1 which theyare finally discharged through the outletdoor opening 20. buitableclosures, not shown, maybe provided for the outlet opening 20 as Well asthe inlet opening 21.

As shown in the drawings, the crucibles around from the outlet-totheinlet and reloaded, and travels again through the "kiln,

as is the usual practice in operating a tunnel kiln.

On account of the relatively longer time of the dehydration firing ofthe crucibles, I prefer to carry out thefirst burning 0 eratlon in aseparate kiln 1, "as indicate in the drawings. However, if desired, theentire burning process may be carried out correspond in its action tothe dehydration burning carried out in the kiln indicated in Figure 1 ofthe drawings.

While I have described the. preferred com- The chamber 14 is ether withthe preferred process and kilns for carrying out such process, it is tobe understood that the invention is not limited to the specific detailsof its preferred embodiment but may be otherwise .embodied within thescope of the following claims:

I claim:

1. As a new article of manufacture, a refractory article consistingprincipally of ture. a

' fractory article consisting principal] graphite and, a porcelain andburned prior to use to a temperature graphite and-a vitritiable ceramicbond, and burned prior to, use to a tem erature above thel vitrificationpoint of the onding matcria 2. As a new article of manufacture, areofgraphite and a vitrifiuble ceramic bon and burned prior -to use to atemperature above 2000 F. 4 i

3. As a new article of manufacture, a refractory article consistingprincipally of graphite and a vitrifiable ceramic bond, and burned priorto use to a temperature between 2000 and 2800 F. v I

4. As a new article ofmanufacture, a refractory article consistingprincipally of aphite and a vitrifiable ceramic bond, and urned prior touse to a temperature suflicient to substantially completely vitrify thebonding material throughout the body of the article toproduce astructure which is hard, strong and substantially impervious to mois- 5.As a new article of manufacture, a refractory article consistingprincipally of onding material,

above the vitrification point of the porcelain I bonding material.

6. As a new article of manufacture, a refractory article consistinprincipally of graphite and a porcelain onding material, and burnedprior to use to a temperature above 2000 F. v

' 7. As a new article of manufacture, a refractory article consistingprincipally of graphite and a vitrifiable ceramic bond, and

urned prior to use to a temperature above the vitrification point of thebonding material and having an adherent glaze formed integral with thebond.

8. As a new article of manufacture, a refractory article consistinprincipally, of graphite and a porcelain nding material and burned priorto use to .a temperature sufiicient to substantiall completely vitrifythe bonding material tirough'outthe body of the article, and to form onthe surface thereof an adherent vitrified bond.

- 9. As a new article of manufacture, a re-- fractory article consistingprincipally of graphite and clay, and containing a fluxing ingredient,and burned prior to use'to a temperature above fusion mg ingredient intoa y which is hard,

of the total mass, an burned a mix conta'ini vbonding glaze integralwith the int of the flux-- strong and substantially impervious tomoisture.

2P0. As a new article of manufacture a refractory article consistingprincipally of graphite and a vitrifiable ceramic bond containing clayand a fluxing ingredien the 11. As anew article of manufacture a re-'fractory article consisting principally of graphite and a vitrifiableceramic bond containing clay and a fluxing ingredient, the bondingmaterial bein over 25% by weight prior to use to a temperature above thefusion point of the fluxing ingredient into a body which is hard, strongand substantially impervious to moisture.

12. As a new article of manufacture, a re the fluxing ingredient into abody which is' hard, strong and substantially impervious to moisture. I

14. The process of making refractory article's', which comprises moldingthem from a mix containing graphite and a ceramic bonding material,burnin the-articles ,to substantially completely de ydrate the bond-'ing materia then oxidizing the graphite at the surface of the article,and, thereafter burning the articles to atem the vitrification point ofthe rial.

15. The process of makin refractory articles, which comprises mol inthem from graphite an a ceramic materi burning the articles .in anon-oxidizing atmosphere, then burning the articles in an oxldingatmosphere, and

nding matethereafter burning the articles at a temfperathe Inn

rature above Y a mix containin thereafter burning the articles in anon-oxidizing atmosphere to a temperature above thel vitrification pointof the bonding materia 17. The rocess of makin refractory articles, whiccomprises moldin them from raphite an a porcelain bonding materia,u'rning the articles in a non-oxidizing atmosphere to dehydrate thebonding material, burning the articles in an oxidizing atmosphere tooxidize the graphite at their surfaces, and thereafter burning thearticles in a non-oxidizin atmosphere to a temperature suflicient tovitrify and mature the orcelain bondin -material throughout the ody ofthe artic es. and form on their surfaces a laze integral with thevitrified bond .in the ody.

rocess of makin refractory ar- 18. The

ticles, whic comprises molding them'from a m x containing graphite and aceramic bonding materlal, burning the articles in a non -oxidizinatmosphere for a sufficient time to dehy rate the bonding material, andthen burning the articles so as to oxidize the graphite in the surfaceskin of-the article and fuse the thus oxidized surface skin into aglaze.

19. The ticles, whic comprises molding the articles from a mix containinraphite and a porcelain bonding materia urni ng the articles in anon-oxidizing atmos cient time to thoroughly de ydrate the bond ingmaterial, burning the articles for a relatively short time in anoxidizing atmosphere tooxidize the graphite in the-surface skin only ofthe, articles, and thereafter liurning the articles ,in a non-oxidizingatmosphere to a temperature above 2000 F. so as to vitrify and maturethe porcelain bonding material throughout the body of the articles andfuse the oxidized surface skin into a glaze.

20. The rocess of making refractory articles, whic comprises moldingthem from a mix containin graphite and a ceramic bonding materia burningthe articles in a non-oxidizing atmosphere, then burning the articles inan oxidizing atmosphere so as to oxidize the graphite at their surface,and

thereafter burningFthe articles to a temperature above 2000 v v p 21.The recess of maln'ng refractory articles, whi comprises, molding themfrom mp4s ticles,,

a mix consisting principally of graphite andprocess of mak in refractory:1r--

here for a sufli my hand.

a mix consistingprincipally of graphite and a vitrifiable ceramicbonding material, and burning the molded articles rior to use to atemperature above the vitri cation point of the bonding material. I

22. The process of making refractory arwhich comprises molding them froma vitrifiable ceramic bonding material, and burning the molded .articlesprior to use to a temperature above 2000 F.

23. The process of makin refractory artil) ticles, which comprlsesmolding them from v a mix consisting principally of graphite and avitrifiable ceramic bonding material,

and burning the moldedarticles prior to use to a temperature sufficientto substantially vitrify the bonded material throughout the bod of thearticle, the proportions of the ingre ients and the burningtemperaturebeing such as to form a body having a structure which ishard, strong andsubstantially inpervious to moisture.

24. The process of making refractory articles, which comprises .moldingthem from a mix consisting principally of graphite and a porcelainbonding material, and burning the articles prior to use to a "temerature sufficient to vitrify the porcelain onding material "and form itinto a glaze at the surface of the article. i

25. The process of making'refractory articles, which comprises moldingthem from a mix containing graphite and a vitrifiable ceramic bondingmaterial, burning the articles to substantially-completely dehydrate butnot fuse the bonding material, and'thereafter burning the articles to atem erature above thevitrification point of the onding material.

26. The process of making refractory arfrom ticles, which comprisesmolding them a mix consisting principall of graphite and a vitrifiableceramic bon containing clay and a fluxing ingredient, burning thearticles 7 at a temperature below the fusion point of the fluxingingredient but sufficiently high to substantially completely dehydratethe bondin arlficles to a temperature above" the fusion point of thefluxing ingredient.

In testimony whereof I have hereunto set ARTHUR J. .momu.

material, and thereafter burning the-

